This chapter summarizes the emerging use of bio-wastes such as rice husks, corn stalks, and sugarcane bagasse etc. coming from plants’ waste for reinforcement is one of the most accepted ways to bring sustainability in fiber reinforced polymer composites. The biowastes are discussed from the point of view of their properties and compositions that allow them to be used as reinforcement in polymer composites. This chapter discusses the recovery, recycling, and utilization of the wastes arising from this category of composite materials. The chapter is focused on the utilization of residual agricultural biomass/natural fiber waste as a promising sustainable construction material in rural areas. The natural/agro based fibers suitable for use in sustainable construction materials are summarized. The effect of fibrous reinforcement on the mechanical, thermal, acoustic and fatigue performance of sustainable construction materials are described. This chapter further addresses the technologies, techniques, challenges, and opportunities linked to the recycling of fiber reinforced polymer composites.